Roller bearings used in industries, such as the oil and gas industry, are exposed to extremely harsh operating conditions during use in on and off shore oil rigs, which place great stress and load on the bearings. For example, off shore oil rigs are driven to be used in increasingly deeper water and it is not unusual for the components thereof, such as tubes, rods and so forth, to extend to a depth of between about 1000 to 1500 feet to reach the sea bed. During operation of the oil rig, these various descended components must also rotate to obtain the proper drilling action. Accordingly, such factors translate to a great load on the top drive bearing located within a top drive system of the oil rig.
The top drive system of an oil rig, in general, typically comprises a flat platform and an arrangement thereon including a top drive bearing for turning the afore-referenced rods, tubes and so forth to cause the desired drilling action. As one can appreciate, the deeper the drilling, the more load is required on the top drive bearing for the rotating and drilling action.
The basic static load rating for a thrust bearing is proportional to the number of rollers (Z) times the roller length (L) times the roller diameter (D). The dynamic load rating for a thrust bearing is proportional to L7/9Z3/4D29/27. Therefore, as the length of the rollers, the number of the rollers, and the roller diameters are increased, the static and dynamic load carrying capability of the bearing increases accordingly. This bearing steel is carburized for use in top drives, a process which imparts additional desired properties to the material.
The life of a thrust roller bearing is proportional to b(C/P)10/3 where P is the applied load, C is the dynamic capacity, and b is a so-called life factor.
A standard, modern day, bearing material is a through hardened vacuum degassed AISI 52100 steel. The well known life factor for this material is b=1.5. Vacuum remelting of the AISI 52100 material reduces the number and size of material inclusions. This processing is known to double the life factor of the same bearing. The life factor thus becoming 3.0.
However, vacuum remelting is an expensive process and adds significantly to the cost of the material.
Accordingly, scientists and engineers working under the direction of Applicants' Assignee are seeking to develop a top drive bearing for use in a top drive system that yields a life factor of at least three (3.0) without the additional cost of vacuum remelting processing.
Embodiments of the present invention address the above need, as well as others.